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'The telescope gave us what might be the greatest discovery of all – the universe itself.' - Jim Al-Khalili

Jim Al-Khalili and a team of experts explore the fascinating story of one of our greatest inventions, the telescope, using original notebooks, stylish visualisations and sophisticated computer graphics. It is a tale full of twists and turns, involving a seashore plant, a New York property boom and a spilt bottle of mercury. Thanks to these events, the telescope allowed us to discover not just our place in the cosmos, but our origins too.

Jim travels to eighth-century Baghdad to witness the first experiments in optics. Many regard this as the birth of science itself, culminating in Ibn al-Haytham’s extraordinary book explaining how light can be manipulated.

In 12th-century Venice, a secret process using a seashore plant allows the manufacture of clear glass and with that, the first precision lenses. 250 years later a Dutch optician makes a chance observation: a particular arrangement of lenses magnifies distant objects. Months later, an Italian mathematics teacher, Galileo, constructs his own version and points it into the night sky. It is a revolution not just in astronomy but also in humanity’s perception of itself.

In Paris, an accident with mercury allows Louis Daguerre to make highly sensitive photographic plates. Now cameras are attached to telescopes allowing celestial images to be analysed with mathematical precision. Later, a New York property boom allows a wealthy donor to fund a full-sky survey. Working on this project, Henrietta Leavitt notices that some stars undergo regular changes in brightness, which allows astronomers to measure their distance from the Earth. Edwin Hubble, using Leavitt’s discovery, measures the vast distances of entire galaxies. Hubble also discovers that the universe is expanding, implying that before the Big Bang, it must all have been in the same place.

With the Hubble Space Telescope, we have reached the limits of our vision, but a new generation of telescope is about to be launched. The James Webb Space Telescope will see as far as it is possible to see, revealing new features of the vast universe we call home.